linux-kernel - Re: [PATCH v11 03/11] firmware: xilinx: Add zynqmp IOCTL API for device control

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Date:   Sun, 23 Sep 2018 14:10:59 +0100
From:   Olof Johansson <olof@...om.net>
To:     Jolly Shah <JOLLYS@...inx.com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        "ard.biesheuvel@...aro.org" <ard.biesheuvel@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "matt@...eblueprint.co.uk" <matt@...eblueprint.co.uk>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Michal Simek <michals@...inx.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-clk <linux-clk@...r.kernel.org>,
        Rajan Vaja <RAJANV@...inx.com>,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>
Subject: Re: [PATCH v11 03/11] firmware: xilinx: Add zynqmp IOCTL API for
 device control

Hi,

Apologies for the slow responses here, I meant to follow up on this sooner.

On Tue, Sep 11, 2018 at 8:20 PM, Jolly Shah <JOLLYS@...inx.com> wrote:
> Hi Sudeep and Olof,
>
> Clock driver from same patch set uses ioctl API along with other clock eemi APIs. As clock patches' final review is pending by Stephen, Michal only created pull request for rest of the patches and that doesn't require ioctl api. I will remove it and submit new patch set.
>
> For future patches which requires ioctl api, would like to understand your suggestion so I can make required changes. For zynqmp, EEMI interface allows clock, reset, power etc management through firmware but apart from those there are some operations which needs secure access through firmware. Examples are accessing some storage registers for inter agent communication, configuring another agent(RPU) mode, setting PLL parameters, boot device configuration etc. Those operations are covered as ioctls as they are very platform specific. Do you suggest to handle them with individual EEMI APIs instead of ioctl API?

I'm personally less worried about whether the calls are through an
ioctl API or an EEMI one, but if it is through ioctl, I'd prefer if it
wasn't wide-open pass-through. I.e. that the ioctls you actually use
are documented, and only those who are whitelisted are passed through
(and not in general exported to userspace).

Does that make sense?


-Olof